[Bugfix]Lazy import vllm config (#462)

### What this PR does / why we need it?
Lazy import vllm config  to avoid circular imports

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

pytest.ini

@@ -43,6 +43,7 @@ norecursedirs =
 addopts = --ignore=vllm-empty/tests/test_utils.py
           --ignore=vllm-empty/tests/test_config.py
           --ignore=vllm-empty/tests/test_scalartype.py
+          --ignore=vllm-empty/tests/test_version.py
           --ignore=vllm-empty/tests/test_embedded_commit.py
           --ignore=vllm-empty/tests/test_inputs.py
           --ignore=vllm-empty/tests/test_sharded_state_loader.py

vllm_ascend/platform.py

@@ -22,7 +22,6 @@ from typing import TYPE_CHECKING, Optional, Tuple
 import torch
 import torch_npu  # noqa: F401
 import vllm.envs as envs
-from vllm.config import CompilationLevel
 from vllm.logger import init_logger
 
 try:
@@ -105,6 +104,7 @@ class NPUPlatform(Platform):
 
     @classmethod
     def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
+        from vllm.config import CompilationLevel  # noqa: E402
         compilation_config = vllm_config.compilation_config
         if compilation_config and compilation_config.level != CompilationLevel.NO_COMPILATION:
             logger.warning(